1. Technical Field
The present invention relates to an electrostatic latent image developing core-shell type toner, a method for manufacturing the toner, and an image forming method using the toner.
2. Description of Related Art
Recently, low temperature fixability of toner has been improved in order to suppress power consumption while achieving high-speed printing and expansion of media adaptability. However, with mere use of a resin that is melted at low temperature, durability at normal temperature cannot be maintained, and problems occur, such as toner blocking and image sticking. To prevent such problems, toners have been developed that use a polyester resin having high glass transition point and low softening point to lower resin melting temperature and simultaneously to maintain high glass transition point so as to be able to provide both low temperature fixability and strengths of toner particles and images against physical stresses at normal temperature. On the other hand, in terms of speeding up printing, there is an increasing need to ensure image quality stability during continuous printing, and toner, after having been supplied into a developing unit, is desired to be quickly electrically charged and allowed to reach a portion to be developed.
As an example of a technique for ensuring such image quality stability during continuous printing, Patent Literature 1 proposes a binder resin for an electrophotographic toner. It is a toner binder resin composed of a resin obtained by subjecting a crystalline resin containing aqueous dispersion solution and an amorphous resin containing aqueous dispersion solution to an aggregation step and a coalescence step. The crystalline resin is a composite resin that includes a polycondensation-based resin component obtained by polycondensation of an alcohol component that contains an aliphatic diol having 2 to 10 carbon atoms and a carboxylic acid component, and a styrene-based resin component.
Patent Literature 1 is Japanese Patent Application Laid-open No. 2011-053494.